Leukocytes and organization of the immune system Flashcards
(30 cards)
What are the main roles of phagocytes?
Defense against bacteria, fungal infections, and tumors
What are alternate names for neutrophils and their lifespan?
Also called polys, pmns, segs; only live for a few hours in peripheral blood
Where are eosinophils found and what are their functions immunologically?
They are usually found in the tissues (not systemic circulation) and wage hypersensitive reactions against parasites, allergens, and some tumors
Where are basophils found and what are their functions immunologically?
They are predominantly found in tissues and are involved in immediate hypersensitivity reactions and release heparin and histamine.
What is the difference between a monocyte and a macrophage and what are their roles?
Monocytes exist in the peripheral blood and macrophages exist in the tissues. Both are involved in ingestion of foreign substances and the presentation to the adaptive immune system. They appear more vacuolated usually than basophils.
Where are mast cells found and what are their functions?
Found predominantly in bone marrow, skin, and the mucosal epithelium,, have histamine and powerful affinity for IgE
During what stages of differentiation is SCF found?
Pluripotent stem cells
During what stages of differentiation is IL-3 found?
From stem cells up to myeloblasts
During what stages of differentiation is GM-CSF found?
From progenitor cells through the seg stages
During what stages of differentiation is G-CSF found?
From late progenitor cells through the seg stages
What is the difference between a circulating seg and a marginating seg?
Marginating cells travel along the edges of the endothelium and enter the tissues readily; stress causes marginating cells to enter the tissue
What are the primary lymphoid organs and their roles?
The bone marrow (where B cells mature) and the thymus (where T cells mature)
What are the secondary lymphoid organs and to what do they respond immunologically?
Lymph nodes respond to tissue antigens
The spleen responds to blood antigens
MALT responds to mucosal antigens
By what means do lymph cells leave the circulation?
Through high endothelial venules
What are the afferent and efferent lymphatic pathways?
Afferent pathways enter a lymph node and efferent pathways are the roads back to the circulation via the thoracic duct.
What are the primary roles of the lymph vessels?
They ferry blood that enters the tissues from hydrostatic pressure into the bloodstream again; lymphocytes and dendritic cells use lymph vessels to travel to lymph nodes
What are the main regions of the lymph node and the relevance of the various domains?
The capsule encloses the node
The subscapular space accepts afferent lymph and is the site of most metastasis
The follicles in the cortex is where B cells mature
The paracortex is where T cells reside
The medullary cord is where plasma cells reside
Where are B lymphocytes predominantly found and how much of circulating lymphocytes do they make up?
Exist mostly in the cortex of lymph nodes, the white pulp of the spleen, and in other lymph
How to naive B cells apppear and where are they found?
They express both IgM and IgD and can respond and present antigen; they are present in primary lymphatic follicles
What are the roles and cell types in a germinal center?
Antigenic activation promotes B cell differentiation. The dark zone is the site of proliferating centroblasts and the light zone is where proliferating centrocytes; selection of self antigens occurs here
How does reactive hyperplasia occur?
Germinal centers in a lymph organ overreact to antigen and proliferate excessively
What is the role of the red pulp of the spleen?
Filters the blood for antigens by macrophages and for the destruction of RBCs
What are the two types of circulation in the red pulp of the spleen?
The open circulation runs through the capillaries into splenic cords to sinusoids and thereafter to veins
The closed circulation is a direct passage from the pencillary arteries to the sinuses and traebecular veins thereafter
What are the roles of white pulp?
The white pulp is predominately immunologic in nature with T cell populations and B cell germinal centers. It is demarcated from the red pulp by the peri-areolar lymphoid sheath
